1999 115hp FICHT motor. When I bought the motor I was told to use Evinrude systhentic oil only. Something do with the computer set up I think. Well the price of this oil is getting high around $40.00 per gal so with putting a lot of hours it starts getting expensive and hard to find. I am thinking of switching over to Amsoil which is alot cheaper. Will this hurt the engine and does anybody know what Amsoil product is comparable Thanks